A lot of developed (HDI greater than 0.8 and GDP per Capita greater than 13k) countries don't have regulations similar to the "Clean Water Act".

Turkey, Hungary, Cyprus, the Baltics outside the capital city, Malaysia, and Romania are great example of that.

I am not entirely sure if Lead or other heavy metal content in Water is consider Drinkable.

true, but significant lead in the water is a failure mode, not considered a normal state of most drinking water in developed areas. Generally, when found, some action is taken to address the contamination (unless there is some other regulatory failure, such as in Detroit).

While lead is generally considered to not be drinkable, even in desperation, no one's putting the Brita water filters on their faucets to remove lead, and it's silly to even suggest it.